Roller board with one or more user-maneuverable trucks and north-seeking return mechanism

ABSTRACT

A roller board device like a skateboard or scooter operated by a user with one or more user-maneuverable wheel assemblies that are automatically returned to their “true north” position is provided according to the invention. The roller board device comprises an elongated deck, at least one wheel assembly, a rotation assembly operatively engaging and extending through the opening in the deck, one end of the rotation assembly being connected to the wheel assembly positioned below the deck, the other end of the rotation assembly being connected to a user interface member extending upward beyond the top surface of the deck, and a north-seeking return mechanism secured to the deck containing an engagement member movable along a linear axis within a housing and engaging a spring disposed between the engagement member and an interior wall of the housing, the rotation assembly operatively connected to the engagement member to convert rotational movement of the rotation member into linear movement of the engagement member. When the user applies rotational force to the user engagement member to turn it to the left or right, the rotation assembly and wheel assembly are rotated in the same direction and degree to allow the roller board device to be turned, the rotated rotation assembly interacting with the engagement member of the north-seeking return mechanism to move the engagement member along its linear axis to a retracted position to compress the spring. But, when the user releases the rotational force upon the user interface member, the spring extends from its compressed state to its elongated state to move the engagement member of the north-seeking return mechanism back along the linear axis from its retracted position to its standby position, counter interacting with the rotation assembly to return the wheel assembly of the roller board device to its true north position.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of U.S. Ser. No. 15/433,842filed on Feb. 15, 2017 which is hereby incorporated in its entirety.

FIELD OF THE INVENTION

The present invention relates to self-propelled roller boards likeskateboards and scooters, and more particularly to a skateboard orscooter with one or more steerable trucks that may be independentlymaneuvered by the user while riding the skateboard or scooter to steerit in a desired direction, and automatically returned to their standby“true north” position once the user is no longer steering them.

BACKGROUND OF THE INVENTION

Skateboarding has become a popular recreation and sport. Derived fromthe late-1940's surfing scene in California as an activity for when thewaves were flat, early skateboards were comparatively primitive devicescomprising wooden boxes with roller skate wheels attached to theirbottom surface. Eventually, the boxes were replaced by wooden plankswith metal or “clay” wheels. In the early 1970's, polyurethane wheelsproviding significantly improved traction and performance wereintroduced. Such skateboards were easier to ride, increasing thepopularity. Today, skateboarding represents a $4.8 billion industry withmore than 11 million active skateboarders in the world. It will becomean Olympic event in 2020.

The user stands with his feet on the skateboard and uses one foot tomanually propel the skateboard forward. The skateboard can also beridden downhill using gravity to propel the device.

A modern skateboard typically features a deck that is 7-10½ inches wideand 28-33 inches long. “Long” boards are usually over 36 inches long.Two metal trucks connect the wheels to the bottom surface of the deck.The wheels of the wheel assemblies rotate along an axle that runsthrough the hanger portion of the truck. A baseplate forms the topportion of the truck and is used to mount the truck to the deck. Rubberbushings positioned between the baseplate and the hanger cushion thetruck when it is turned. Each of the wheels is mounted on its axle viatwo bearings.

The wheel truck assemblies are typically mounted to the skateboard in afixed relationship without any ability to pivot the wheels to steer.Instead, the user must lean sideways while riding the skateboard toshift his center of gravity away from the skateboard to turn theskateboard to the left or right. This action requires balance andcoordination by the user and can provide challenges to a beginner ornovice rider.

The need for a more-maneuverable skateboard arises for a user who isengaging in skateboard tricks which has become a sport in its own right.Once content with two-dimensional freestyle tricks such as wheelies,manuals, and pivots, popular skateboard tricks have become morecomplicated, three-dimensional, aerial maneuvers. For example, an“ollie” jump is accomplished by snapping down the tail of the skateboardand sliding the user's front foot forward to launch the skateboard inthe air. While floating in the air, the user can use his hand to holdthe skateboard against his feet in a maneuver called an “indy grab,”Often times, aerial rotations are combined to produce a “kick flip.”Riding the skateboard's deck or truck along a street curb, ledge, orrail yields a “slide” or “grind,” respectively. Specially-builtskateboard parks with ramped surfaces provide the perfect environmentfor these highly imaginative and acrobatic aerial maneuvers, whichrequire the user to produce quick turns on his skateboard.

U.S. Pat. No. 4,955,626 issued to Smith, et al. discloses a devicecomprising two skateboards connected to each other by means of a spacerelement. The user stands with his left foot on the one skateboard andhis right foot on the other skateboard. By shifting body weight relativeto the two feet, the user can pivot the skateboards inwards or outwardswith respect to the longitudinal direction of travel to execute a turn.But this device requires more balance and coordination then many userscan muster.

U.S. Pat. No. 6,511,083 issued to Tsai discloses a skateboard featuringa rear wheel assembly that is fixed with respect to the longitudinalaxis of the deck, and a front wheel assembly that pivots with respect tothe longitudinal axis by means of a steering shaft that extendsvertically from the deck. While convenient for a user riding along astreet or sidewalk for recreation, this steering shaft can interferewith aerial trick maneuvers. It can also provide a safety hazard to theuser.

U.S. Pat. No. 3,069,182 issued to Hufford in 1962 provides an example ofa four-wheeled coaster wagon that a user rides in along adownwardly-ramped surface. The front axle assembly is mounted to turn bymeans of a handle bar around a vertical bolt with respect to the wagoncarriage. A disc positioned between the carriage and wheel assemblyprovides high resistance against the front axle turning when a wheelstrikes an obstruction. A compression spring connected between this discand the bottom of the chassis of the wagon further limits the degree towhich the front axle may be turned upon impact with an impediment, andbiases the front wheels to their centered position. However, the limitedability of the compression spring to pull the front axle back to its“true center” position is acceptable, because the user may easily usethe handle bar to steer the wagon.

More advanced skateboarders demand skateboards that are moremaneuverable to allow them to perform tricks like jumps and spins. U.S.Pat. No. 4,160,554 issued to Cooney discloses a conventional skateboardhaving non-pivotable front and rear axle assemblies, but with a “lazySusan”-like rotating disk mounted to the top surface of the board. Theuser stands on top of the disk and can turn the disk and his body withrespect to the independently moving skateboard as it is propelled by theuser's foot in a linear direction. But the user still must rely uponleaning towards the left or right sides and shifting his weight withrespect to the longitudinal axis of the skateboard to turn it, becauserotating the disk does not rotate the front or rear axle assemblies.Thus, the skateboard according to Cooney does not provide the kind ofmaneuverability required for tricks. This is particularly the case fornovice skateboarders. See also U.S. Pat. No. 4,230,330 issued toMuhammed.

U.S. Pat. No. 3,771,811 issued to Bueno does disclose a skateboardexhibiting some degree of axle maneuverability. The front axle assemblyis fixed with respect to the longitudinal axis of the skateboard. Therear axle assembly pivots with respect to the skateboard and is mountedto a circular platform above the top surface of the board. The userplaces his left foot on the front portion of the board, and his rightfoot on top of the circular platform. By turning his right foot, hepivots the circular platform and the rear axle assembly mounted theretoin a crude manner to turn the skateboard. However, the user's right footis positioned above the left foot which can throw off balance. Moreover,the large circular platform extends from the rear end of the skateboard,which interferes with the downward stomp exerted by users on the rearend of the board necessary for executing jump tricks. It is alsodifficult for the user to control the maneuverability of the rear axleassembly given the simple nature of the mechanism, nor does the axleassembly return to its true forward-facing position on its own.

U.S. Pat. No. 4,202,559 issued to Piazza, Jr. discloses a similarskateboard construction, but where the rear axle assembly is fixed withrespect to the longitudinal axis of the skateboard, while the front axleassembly is pivotably mounted to the board by means of a hollow bearingthat passes through a bearing collar affixed to the circumference of ahole formed in the board. A steering platform rests on top of the hollowbearing and above the skateboard. A torsion spring is positioned insidethe hollow bearing with one end connected to the steering platform andits other end connected to the skateboard to limit the radius ofpivotable steering of the front axle. The user stands with his rightfoot on top of the steering platform and can turn the platform with hisfoot to pivot the front axle assembly. When the user releases therotational force applied to the steering platform, the torsion spring“tends to act to return the steering platform to its normal standbyorientation.” But this single torsion spring only provides limitedability to bias the steering platform and its axle.

U.S. Pat. No. 8,608,185 issued to Dermal discloses a skateboard truckassembly with an integrated combination of gears resembling planetarygears that allow both wheels and a caster to remain on the ground whilethe skateboard travels along the longitudinal axis. When the user leansto the left side or right side, the gear assembly causes the “downhill”wheel to rise in the air and the caster to be displaced so that the usercan slide or drift laterally as though he were riding a snowboard down aski slope. The raised downhill wheel will not catch any streetirregularities or rocks that would stop the skateboard from rolling.While this type of skateboard provides a degree of lateral slidingmaneuverability, it does not al low an axle assembly to be directlypivoted by the skateboarder with his foot to turn the skateboard.

U.S. Pat. No. 8,925,936 filed by one of the inventors of the presentApplication and owned by the Applicant of this Application discloses askateboard having a user engagement member rotatably mounted inside theboard that is directly connected to the truck and axle assembly. Theuser engagement member can be operated by the foot of a user standing ontop of the moving skateboard. With two such truck and axle assembliesmounted to the skateboard, the user may turn the front and rear axlesindependently of each other. The trucks can be rotated 360°. But, theuser still must keep track of the pivoted position of each axle withrespect to the longitudinal axis of the skateboard to counter turn theuser engagement member to return the axle hack to its standby,forward-facing position after a turning or spinning maneuver has beenexecuted before approaching the next maneuver. It can be difficult tocounter turn the user engagement members to the axle's standby positionnecessary to achieve this “true north” position while the skateboard ismoving, which can harm the user's confidence in executing tricks.Moreover, a skateboard having its two axle assemblies pointed indifferent directions will typically provide an unstable ride with thetip or tail of the skateboard nose diving. This increases the risk ofwipeouts and injury to a beginner or skilled user.

Meanwhile, scooters are popular recreational vehicles for children.Consisting generally of a narrow foot board mounted between two wheelstandem with an upright steering handle attached to the front wheel, thechild places one foot on the scooter board, while using the other footto push off the ground to provide the necessary motive force. Thesteering handle provides direct maneuverability to the user of the frontwheel. But the turned wheel does not return to its “true north” positionunless it is counter turned by the user.

Thus, it would be beneficial to produce a skateboard or scooterstructure having independently pivotable front and rear axle assembliesmounted to foot disks operatively turned by the user's feet standing ontop of the moving skateboard where the axle assemblies automatically arereturned to their true north positions with respect to the longitudinalaxis of the board when the turning force is released from the user footdisks within the board. Likewise, a scooter having a front wheel that ismaneuvered by a steering handle coupled with a north-seeking returnmechanism when the user no longer is exerting turning force on thesteering handle would also be highly beneficial.

SUMMARY OF THE INVENTION

A roller board device like a skateboard or scooter operated by a userwith one or more user-maneuverable wheel assemblies that areautomatically returned to their “true north” position is providedaccording to the invention. The roller board device comprises anelongated deck having a longitudinal axis and one or more openingsextending through the deck, the deck having a top surface and a bottomsurface; at least one wheel assembly comprising a truck and axle with atleast one wheel rotatably mounted to the axle; a rotation assemblyoperatively engaging and extending through the opening in the deck, oneend of the rotation assembly being connected to the wheel assemblypositioned below the deck, the other end of the rotation assembly beingconnected to a user interface member extending upward beyond the topsurface of the deck; and a north-seeking return mechanism secured to thedeck, the north-seeking return mechanism having a housing containing anengagement member movable along a linear axis within the housing andengaging a spring disposed between the engagement member and an interiorwall of the housing, the rotation assembly operatively connected to theengagement member to convert rotational movement of the rotation memberinto linear movement of the engagement member. In its true northposition, the axle of the wheel assembly is substantially transverse tothe longitudinal axis of the deck with the engagement member in itsstandby position along the linear axis inside the north-seeking returnmechanism housing. When the user applies rotational force to the userengagement member to turn it to the left or right, the rotation assemblyand wheel assembly are rotated in the same direction and degree to allowthe roller board device to be turned, the rotated rotation assemblyinteracting with the engagement member of the north-seeking returnmechanism to move the engagement member along its linear axis to aretracted position to compress the spring. But, when the user releasesthe rotational force upon the user interface member, the spring extendsfrom its compressed state to its elongated state to move the engagementmember of the north-seeking return mechanism back along the linear axisfrom its retracted position to its standby position, counter interactingwith the rotation assembly to return the wheel assembly of the rollerboard device to its true north position.

In its preferred embodiment, the rotation assembly comprises a crankshaft having a drive peg extending from its bottom surface, and a crankshaft receptor having a through hole for accepting the drive peg. Anopening is formed within the engagement member having a leading edge anda trailing edge, the drive peg of the crank shaft extending through theopening in the engagement member. When the rotation assembly is turnedby the user force applied to the user interface member, the crank shaftand crank shaft assembly are rotated in the same direction and degree asthe user interface member to turn the wheel assembly of the roller boarddevice, and the drive peg along the rotated crank shaft bears againstthe trailing edge of the opening of the engagement member of thenorth-seeking return mechanism to move it along the linear axis to itsretracted position. When the user ceases to apply rotational force tothe user interface member and the spring in the north-seeking returnmechanism housing expands from its compressed state, the leading edge ofthe opening of the engagement member bears against the drive peg tocounter-rotate the crank shaft and crank shaft receptor to their standbypositions, thereby returning the wheel assembly to its true-northposition. One or more roller bearings may be added to the rotationassembly to enhance the reliable operation of the rotation assembly asit is turned by means of the user interface member to turn the wheelassembly of the roller board device.

In its preferred embodiment, the engagement member of the north-seekingreturn mechanism comprises a Scotch yoke. Moreover, at least one pistonrod is provided inside the north-seeking return mechanism housing alongwhich the engagement member is moved along the linear axis between itsstandby position and its retracted position. This provides additionalstability for the linear motion of the engagement member so that it canbe reliably moved between its standby position and its retractedposition. The spring that is compressed by the engagement member as itis moved along the linear axis to its retracted position, and expands toreturn the engagement member along the linear axis to its standbyposition is preferably a compression spring.

In the case of the skateboard, the user interface member can be a footpad attached to the top of the rotation assembly, the foot padpreferably extending slightly above the top surface of the skateboarddeck to enable the user to easily find the foot pad by touch of hisfoot. In the case of the scooter, the user interface member can be avertical post and handle bar extending upwardly from the scooter deck.The skateboard or scooter may feature two user-maneuverable wheelassemblies which can be operated independently of each other.

The forward edge of the opening in the engagement member can feature aV-shaped surface along which the drive peg of the crank shaft moves tofacilitate return of the engagement member of the north-seeking returnmechanism to its standby position and the wheel assembly to its truenorth position.

A limiter plate may be prepositioned within the housing of thenorth-seeking return mechanism with respect to the engagement member tolimit the movement of the engagement member along its linear axis, andconsequently the degree of rotation of the wheel assembly with respectto the longitudinal axis of the deck of the roller board device. Thiscan be helpful to novice users who are learning how to ride a skateboardor scooter, or perform aerial tricks.

A simpler north-seeking return mechanism includes a housing attached tothe bottom of the roller board deck into which the crank shaft attachedto the foot pad depends. Two coil springs are also contained inside thehousing. One end of each of the springs is attached to the 9:00 (left)and 3:00 (right) side positions, respectively, of the crank shaft. Theother ends of the compression springs are attached to the forwardinterior wall of the housing.

When the user's foot turns the foot pad, e.g., in a clockwise direction,the wheel assembly will be turned in a rightward direction via theinterlocking crank shaft, crank shaft receptor, truck plate, and wheelassembly that are operatively connected to the rotated foot pad.Bearings contained inside the upper and lower bearing housings ensuresmooth turning operation. At the same time, the clockwise turning of thefoot pad will compress one coil spring and stretch the other coilspring. When the user removes the rotational force applied by his footto foot pad, the energy stored in the springs will cause compressionspring to push the crank shaft in a counterclockwise direction, whilecompression spring pulls the crank shaft also in the counterclockwisedirection, thereby resulting in the foot pad and wheel assembly beingcounter-rotated toward the true-north position. If compression springsand are properly balanced in terms of their length and resistance, thismechanism will result in the wheel assembly recovering its true-northposition. This alternative north-seeking return mechanism shouldaccommodate approximately a 90 degree range of rotation for the wheelassembly, instead of the 360 degree range of rotation permitted by theScotch yoke of the previously described true-north return mechanism.

Yet another embodiment of a north-seeking return mechanism comprises aflat-plane crankshaft. It is vertically mounted in its housing along avertical axis. A connecting rod comprises a piston with a circularlinkage at its one end. The circular linkage surrounds the eccentricallymounted wing of the crankshaft. A foot pad is attached to the inletcrank portion of the crankshaft. The outlet crank portion 612 isattached to the truck plate of the wheel assembly. In this manner, whenthe user's foot rotates the foot pad in the clockwise orcounterclockwise direction, the crankshaft will be rotated inside thehousing in the same direction and to the same degree as the rotated footpad, as will the wheel assembly that is connected to the outlet crankportion of the crankshaft. Meanwhile, a compression spring surrounds thepiston portion of the connecting rod. Its one end touches the shoulderof the connecting rod, while its other end touches pivot block thatengages the distal end of the connecting rod.

In its true-north position for the wheel assembly where its axle istraverse to axis of the deck, the vertical intermediate leg of theplanar crank shaft is the furthest distance from the piston block. Inthis position, the connecting rod is withdrawn as fully as possibleforward or rearward from the support tube of the deck. The compressionspring resides in its low-energy state.

But, when the crankshaft is rotated in a clockwise or counterclockwisedirection by means of the foot pad, the eccentrically-oriented wing andits vertical intermediate leg will be rotated in an are towards thesupport tube. This will cause the connecting rod that is rotatablyconnected to the crankshaft's vertically intermediate leg by means ofcircular linkage end to extend into the hollow tubular support,contracting compression spring in the process.

When the user's foot releases the rotational force from the foot pad,the stored energy in the retracted compression spring will cause thespring to expand to its original length to push against the shoulder ofconnecting rod to extend the connecting rod outwardly from pivot blockand out of the tubular support, counter-rotating the crankshaft in theprocess to return it to its true-north position. Thus, thisnorth-seeking return mechanism converts the rotational movement of thecrankshaft into linear movement of the connecting rod similarly to thenorth-seeking return mechanism translating the rotational movement ofcrankshaft into linear movement of Scotch yoke. Moreover, mechanismenables 360 degree rotation and counter rotation of the wheel assemblyjust like mechanism 42 achieves. The foot pad and wheel assembly canalso be turned by the user in a counterclockwise direction with the sameeffect.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is a perspective view of the skateboard having user-maneuverabletrucks with a north-seeking return mechanism of the present invention.

FIG. 2 is a bottom perspective view of the skateboard of FIG. 1 with therear wheel assembly removed for the sake of clarity.

FIG. 3 is an exploded perspective view of the skateboard of the presentinvention.

FIG. 4 is a top partial perspective view of the skateboard deck for theskateboard.

FIG. 5 is a bottom partial perspective view of the skateboard deck ofFIG. 4.

FIG. 6 is a top perspective view of the upper bearing housing for theskateboard.

FIG. 7 is a bottom perspective view of the upper bearing housing of FIG.6.

FIG. 8 is a bottom perspective view of the north-seeking returnmechanism housing for the skateboard.

FIG. 9 is a top perspective view of the housing of FIG. 8.

FIG. 10 is a bottom perspective view of the lower bearing housing forthe skateboard.

FIG. 11 is a top perspective view of the lower bearing housing of FIG.10.

FIG. 12 is a perspective view of the roller bearing for the upperbearing housing and lower bearing housing for the skateboard.

FIG. 13 is a perspective view of the snap ring for the upper bearinghousing and lower bearing housing for the skateboard.

FIG. 14 is a top perspective view of the crank shaft for the skateboard.

FIG. 15 is a bottom perspective view of the crank shaft of FIG. 14.

FIG. 16 is a top perspective view of the foot disk for the skateboard.

FIG. 17 is a bottom perspective view of the foot disk of FIG. 16.

FIG. 18 is a top perspective view of the crank shaft receptor for theskateboard.

FIG. 19 is a bottom perspective view of the crank shaft receptor of FIG.18.

FIG. 20 is a front perspective view of the truck assembly for theskateboard.

FIG. 21 is a rear perspective view of the truck assembly of FIG. 20.

FIG. 22 is a top perspective view of the truck plate for the skateboard.

FIG. 23 is a bottom perspective view of the truck plate of FIG. 22.

FIG. 24 is a top perspective view of an alternative embodiment of thenorth-seeking return mechanism having integrally formed therein thestructural features of the lower bearing housing.

FIG. 25 is a top perspective view of the modified housing of FIG. 24.

FIG. 26 is an exploded perspective view of the north-seeking returnmechanism for the skateboard.

FIG. 27 is a top perspective view of the Scotch yoke tier thenorth-seeking return mechanism.

FIG. 28 is a bottom perspective view of the Scotch yoke of FIG. 27.

FIG. 29 is a cut-away view of the north-seeking return mechanism in itsstandby “true north” position.

FIG. 30 is a cut-away view of the north-seeking return mechanism in itspartially-turned position.

FIG. 31 is a cut-away view of the north-seeking return mechanism in itsfurther-turned position.

FIG. 32 is a cut-away view of the north-seeking return mechanism withthe rotation limitation plate inserted to control the turning arc of thewheel assembly of the skateboard.

FIG. 33 is a cut-away view of the north-seeking return mechanism withthe rotation limitation plate inserted and blocking further turning ofthe rotated wheel assembly of the skateboard.

FIG. 34 is a cut-away view taken along line 34-34 in FIG. 2 of theskateboard's user-maneuverable trucks and north-seeking return mechanismin their assembled state.

FIG. 35 is a perspective view of the scooter having twouser-maneuverable trucks with a north-seeking return mechanism of thepresent invention.

FIG. 36 is a bottom perspective view of the scooter of FIG. 35 with adouble front wheel assembly, and the rear wheel assembly removed.

FIG. 37 is a bottom perspective view of the scooter of FIG. 35 with asingle front wheel assembly, and the rear wheel assembly removed.

FIG. 38 is an exploded perspective partial view of the scooter of thepresent invention with the deck removed.

FIG. 39 is an enlarged exploded perspective partial view of FIG. 38.

FIG. 40A is an exploded perspective view of the skateboard of thepresent invention, containing the retaining plate for the lower bearinghousing, an enlarged foot disc.

FIG. 40B is a perspective view of the skateboard containing enlargedfoot disks and associated user-maneuverable trucks and wheel assembliesin the forward and rear positions.

FIG. 41 is a perspective view of the retaining plate.

FIG. 42 is cut-away, bottom perspective view of the retaining plate ofFIG. 41 attached to the lower bearing housing.

FIG. 43 is a cut-away view of the north-seeking return mechanism withspacers positioned along the piston rods to apply a preload of forceupon the compressions springs.

FIG. 44 is cut-away view of the north-seeking return mechanism withadjustable nuts positioned along the piston rods to apply a preload offorce upon the compressions springs.

FIG. 45 is a bottom perspective view of the foot disc, user-maneuverabletrucks and north-seeking return mechanism assembly with low-frictionpads secured to the bottom surface of the foot disc.

FIG. 46 is a plan view of an alternative tubular structure for the deckof the skateboard.

FIG. 47 is a cut-away plan view of a second embodiment of thenorth-seeking return mechanism of the present invention.

FIG. 48A is a side view of an alternative skateboard containing athird-embodiment of the north-seeking return mechanism shown in itsstandby, true-north position.

FIG. 48B is a side view of an alternative skateboard containing athird-embodiment of the north-seeking return mechanism shown in itsfully-retracted, true-south position.

FIG. 49A is a side view of the FIG. 48A third-embodiment of thenorth-seeking return mechanism shown in its standby, true-northposition.

FIG. 49B is a side view of the FIG. 48B third-embodiment of thenorth-seeking return mechanism shown in its fully-retracted, true-southposition.

FIG. 50A is a plan view of the crank shaft, connecting rod, andcompression spring of the FIG. 49A third-embodiment of the north-seekingreturn mechanism shown in its standby, true-north position.

FIG. 50B is a plan view of the mechanism of FIG. 50A at the 45 degreerotated position.

FIG. 50C is a plan view of the mechanism of FIG. 50A at the 90 degreerotated position.

FIG. 50D is a plan view of the mechanism of FIG. 50A at the 180 degreerotated position which corresponds to FIGS. 49B and 48B.

FIG. 50E is a plan view of the mechanism of FIG. 50A at the 270 degreerotated position.

FIG. 50F is a plan view of the mechanism of FIG. 50A at the 315 degreerotated position.

FIG. 51 a perspective view of the scooter with a raked handle bar post.

FIG. 52 is an exploded view of the mechanism for mounting the raked handbar post of FIG. 51 to the scooter.

DESCRIPTION OF THE PREFERRED EMBODIMENT

A roller board device like a skateboard or scooter operated by a userwith one or more user-maneuverable wheel assemblies that areautomatically returned to their “true north” position is providedaccording, to the invention. The roller board device comprises anelongated deck having a longitudinal axis and one or more openingsextending through the deck, the deck having a top surface and a bottomsurface; at least one wheel assembly comprising a truck and axle with atleast one wheel rotatably mounted to the axle; a rotation assemblyoperatively engaging and extending through the opening in the deck, oneend of the rotation assembly being connected to the wheel assemblypositioned below the deck, the other end of the rotation assembly beingconnected to a user interface member extending upward beyond the topsurface of the deck; and a north-seeking return mechanism secured to thedeck, the north-seeking return mechanism having a housing containing anengagement member movable along a linear axis within the housing andengaging a spring disposed between the engagement member and an interiorwall of the housing, the rotation assembly operatively connected to theengagement member to convert rotational movement of the rotation memberinto linear movement of the engagement member. In its true-northposition, the axle of the wheel assembly is substantially transverse tothe longitudinal axis of the deck with the engagement member in itsstandby position along the linear axis inside the north-seeking returnmechanism housing. When the user applies rotational force to the userengagement member to turn it to the left or right, the rotation assemblyand wheel assembly are rotated in the same direction and degree to allowthe roller board device to be turned, the rotated rotation assemblyinteracting with the engagement member of the north-seeking returnmechanism to move the engagement member along its linear axis to aretracted position to compress the spring. But, when the user releasesthe rotational force upon the user interface member, the spring extendsfrom its compressed state to its elongated state to move the engagementmember of the north-seeking return mechanism back along the linear axisfrom its retracted position to its standby position, counter interactingwith the rotation assembly to return the wheel assembly of the rollerboard device to its true-north position.

The skateboard 10 of the present invention having one or moreuser-maneuverable trucks and a “north-seeking” self-returning mechanismis shown in FIGS. 1-2, it comprises an elongated deck 12 made from anappropriate material such as wood, fiberglass, nylon, plastic or aKevlar composite material. The deck 12 has a top surface 46 and a bottomsurface 48. It also typically features a rounded front end 14 and arounded rear end 16 that avoids sharp edges that could collide with acurb, wall, or other impediment where a user is riding the skateboard,or injure the user during a fall or crash. The deck 12 will beapproximately 28-33 inches long for standard boards, and approximatelyup to 48 inches long for long boards. The deck 12 may optionally containalong all or a portion of its top surface 46 a traction panel made froma traction-providing material like abrasive coated grip tape or coatingpaint containing abrasive particles like sand to help to maintain theuser's foot from slipping off the board. The bottom surface 48 of thedeck 12 may contain graphical material used to provide an appealingdesign to the skateboard. If this graphical design element is addedinstead to the top surface 46 of the deck 12, then clear grip tape maybe used for the traction panel in order not to interfere with thegraphical element. Finally, the skateboard 10 has a longitudinal axisA-A running along its length L.

Mounted to the bottom surface 48 of skateboard deck 12 are a pluralityof wheel assemblies 20, typically two in number shown as 20 and 22. Onewheel assembly 20 should be located near the front of the deck, and theother wheel assembly 22 should be located near the rear of the deck toprovide a stable ride to the user. Each wheel assembly 20, 22 comprisesa truck 24 having a flat planar top surface 26, and a transverse axle 28connected to its bottom surface 30 via a hanger 29. Wheels 32 areconnected to each end of the axle 28. The wheels are made from asuitable material like polyurethane or other polymer plastic thatprovides traction and durability over time as the skateboard is riddenby the user on abrasive surfaces like concrete or asphalt, while alsoproviding some measure of cushion to the user as the skateboard wheelstravel over bumps along the riding surface like a street, driveway,sidewalk, trail, or ramped skateboard park. In its standby position, thetransverse axle 28 is defined by transverse axis T-T which isapproximately perpendicular to longitudinal axis A-A of the skateboarddeck 12. In this manner, the skateboard 10 travels on its wheels in aforward or backwards direction substantially parallel to longitudinalaxis A-A.

At least one of the wheel assemblies 20, 22 of skateboard 10 may bepivotable so that the transverse axis T-T of the axle 28 can bemaneuvered, by the user's foot to turn at an angle ∝ with respect to thelongitudinal axis A-A of deck 12 that is greater than or less than 90°.This pivotable wheel assembly may be mounted to the front portion orrear portion of the skateboard. The other wheel assembly (not shown) maycomprise a transverse axle 28 that is fixed with respect to thelongitudinal axis A-A as is known in the prior art. Alternatively, thisother wheel assembly may comprise a second pivotable wheel assembly thatalso can be maneuvered by the user's other foot while riding theskateboard. In the case of two such pivotable wheel assemblies 20, theymay be maneuvered by the user's two feet independently with respect toeach other. The pivotable wheel assemblies 20, 22 may be maneuvered bythe user along a full 360° arc of motion. Alternatively, the permittedarc of motion may be restricted to less than 360°, as described below.

The skateboard assembly 40 of the present invention havinguser-maneuverable wheel assemblies 20, 22 and a north-seeking returnmechanism 42 are shown in the exploded view of FIG. 3. In the case wherethe skateboard 10 features two user-maneuverable wheel assemblies 20,22, the deck 12 of the skateboard comprises a pair of openings 44. Asshown more clearly in FIGS. 4-5, each opening is preferably circular inshape defined by inner wall 46, although any other shape will suffice.The inner wall 46 is interrupted by a plurality, preferably four, ofcars 48 extending outwardly from the inner wall ring 46. Annular ledge50 having bottom surface 52 and side wall 54 is formed within the upperportion of the deck surrounding the perimeter of the inner wall ring(see FIG. 4).

As shown more clearly in FIG. 5, the bottom surface 48 of the skateboarddeck 12 features a pair of partially-recessed regions 56 and 58positioned along each side of opening 44 running parallel to thelongitudinal axis A-A of the deck. The regions extend partially into thebottom surface of the deck 12 and features partially-cylindricalrecessed central portions 56 a and 58 a terminating in recessed squareend portions 56 b and 58 b at each end of the central portions 56 a and56 b. These square regions 56 b and 58 b are partially depressed intothe deck 12. Perimeter walls 59 are formed within the deck 12 around thesquare perimeters of the square recessed regions 56 b and 58 b and thebottom surface 48 of the deck. These perimeter walls are preferably ⅜inch high and provide abutment surfaces for securing in place the squarecorner bosses 88 of the housing 84 for the north-seeking returnmechanism 42, as described below. Note that other shapes for recessedregions 56 b and 58 b are possible as long as they mirror the shapedfeatures of the housing 84. Meanwhile, partially cylindrically-shapedrecessed regions 56 a and 56 b of the deck 12 cooperate with partiallyrecessed wells 94 and 95 formed in housing 84 to provide cylindricalchambers for the springs of the north seeking return mechanism 42, asdescribed more fully below.

Bearing housing 60 is shown more clearly in FIGS. 6-7. It comprises adisk portion 62 having a top surface 64 and a bottom surface 65. Disk 62has a circular opening 63. Extending downwardly from the disc portion isannular ring wall 66 having an outer surface 68, inner surface 70, andbottom planar surface 72. Four lugs 74 extend outwardly from annularring wall 66 with their rounded outside surfaces contributing to theouter perimeter of annular ring wall 66. Through bores 76 extenddownwardly through the lugs 74.

The diameter of opening 63 of bearing housing is approximately 2-2½inches. The height of surface 67 of the inner surface 70 of annular ringwall 66 is approximately ⅜ inches.

The bearing housing 60 may be made from any suitable material providingthe required combination of strength and lightweightness like aluminum,steel, polycarbonate, or polyethylene. 1 t is preferably formed fromcast aluminum.

The housing 84 for the north-seeking return mechanism 42 for theuser-maneuverable wheel assembly is shown in greater detail in. FIGS.8-9. It comprises a main body 80 having a flat exterior surface 82 andside walls 84 and 86. Square-shaped bosses 88 extend upwardly from thefour corners of side walls 84 and 86. The bosses 88 have a flat planarbottom surface 90. Channel 92 extends through the side of each boss withchannels 92 a and 92 b being co-axial. Channels 92 c and 92 d likewiseare co-axial. Open-faced wells 94 that constitute a roughly halfcylinder are formed within side walls 86 between the square bosses.

Main body 80 of housing 84 also has a circular opening 98 defined byinner wall 100 that is interrupted by a plurality, preferably four, ofears 102 extending outwardly from inner wall ring 100. The main housingbody 80 may be made from a 3D-printed polymer material likepolycarbonate. But it is preferably formed from cast aluminum due to thecombination of strength and lightweightness of this material. Thecircular opening 98 is approximately 2½-3 inches in diameter. Therounded region 103 of ears 102 is approximately ⅜ inch in diameter. Theinner ring wall 102 and interior surface of ears 102 need only beapproximately 1/16 inch tall to provide an abutment surface for theannular ring wall 66 and lugs 74 of the bearing housing.

Another shape besides a circle can be used for opening 98 and inner ringwall 100. However, the openings 98 and 44, ring walls 100 and 46, andears 102 and 48 for the respective housing 84 and skateboard deck 12should be similar in shape and dimensions to coordinate with the shapeand dimensions of annular ring wall 66 and lugs 74 of bearing housing60.

Lower bearing housing 110 is shown in FIGS. 10-11. It preferably is madeof the same design, shape, and dimensions as those pertaining to upperbearing housing 60. The same numbers for the various parts of upperbearing housing 60 shown in FIGS. 6.7 are therefore used for thecorresponding parts of lower bearing housing shown in FIGS. 10-11.

Upper hearing 116 is shown in FIG. 12, it comprises a roller bearingmechanism that is known in the art. It is preferably circular in shapehaving an outer ring wall 118 called a “race” with an exterior surface120 and an inner ring wall 122 with an inner surface 124. The outer ringwall 118 and inner ring wall 122 cooperate to define an annular channel124 there between. A plurality of spherical ball bearings 126 made fromhardened steel (not shown) are positioned inside annular channel 124around the perimeter of the roller bearing 116. Such a roller bearing116 may be sourced from the Silverthin Bearings Group of Mechatronics,Inc. of Preston, Wash. The ball bearings come with the roller bearingproduct.

Upper roller bearing 116 is press fit into the cylindrical chamber 65formed inside upper bearing housing 60 defined by side wall 70 andbottom ledge wall 69, and peripheral lip 71. In this manner, exteriorsurface 120 of roller bearing 116 abuts side wall 70 of upper bearinghousing chamber 65, while the bottom surface of roller bearing 116 abutsbottom ledge wall 69 of upper bearing housing 60. Peripheral lip 71 ofthe upper bearing housing 60 extends partially over the top of rollerbearing 116 to keep it securely in position inside chamber 65 of upperbearing housing 60. Snap ring 130 (see FIG. 13) is then snapped intoposition to engage peripheral lip 71 of the bearing housing and keeproller bearing 116 in a fixed relationship to the upper bearing housing60. The plurality of ball bearings 126 contained inside annular channel124 (not shown) extend above the roller bearing inside chamber 65.

Crank shaft 140 is shown in FIGS. 14-15. It comprises a main body 142and an annular skirt 144 extending laterally from the bottom of the mainbody. The main body side walls 146 yield to a tapered periphery 148 anda flat top surface 150. A plurality (preferably five) of threadedthrough bores 152 are formed inside upper body 142 around the perimeterof top surface 150. The bores have chamfered top portions 154 toaccommodate the heads of bolts 192. (see FIG. 3). The crank shaft isfabricated from a strong material that is easy to machine, such as 316stainless steel.

As shown in FIG. 14, extending from bottom surface 156 of crank shaft140 is drive peg 158. It is approximately cylindrical in shape havingexterior surface 160. The drive peg 158 may be made from steel.Alternatively, all of crank shaft 140 may be made from the same steelmaterial. Bushing 162 fits around drive peg 158 (see FIG. 3). It may bemade from silicon bronze. The bushing 162 provides a lubricatedinterface between the drive peg 158 and the Scotch yoke 308 of thenorth-seeking return mechanism.

Crank shaft 140 is inserted into the open chamber 63 of upper bearinghousing 60 with side wall 146 of the crank shaft abutting interior wall124 of roller bearing 116. Peripheral skirt 144 of crank shaft 140 abutsbottom surface 72 of the upper bearing housing. Meanwhile the upperbearing housing 60 is inserted into opening 44 formed in skateboard deck12 with exterior surface 68 of annular ring wall 66 abutting inner wall46 of the skateboard opening and lugs 74 in the upper bearing housing 60fitting inside ears 48 with the skateboard deck 12. Bottom surface 65 ofdisk 62 of upper bearing housing 60 abuts surface 52 of annular region50 surrounding the opening 44 in the skateboard deck 12. This depressedannular region 50 enables the disk 62 of the upper bearing housing 60 tosit inside the depressed region with the top surface 64 of the upperbearing housing 60 being relatively co-planar with the top surface 46 ofthe skateboard deck 12. A plurality of bolts 170 pass through channels76 formed inside lugs 74 of upper bearing housing 60 and into threadedholes 172 formed in the housing 84. In this manner, upper bearinghousing 60 is secured to housing 84 of the north-seeking returnmechanism 42 with the skateboard deck 12 contained between these twohousings which are fixed in place with respect to the deck.

At the same time, crank shaft 140 can freely turn inside the opening 44in the skateboard deck contained between the upper bearing housing 60and housing 84. Foot disk 180 is shown in FIGS. 16-17. It comprises abody 182 formed from a durable material like cast aluminum. A furthertraction enhancement material like grip tape can be added to the topsurface 184 of the body 182 to provide traction for the user's foot, orelse ribs can be molded into the top surface of the disk to help toprevent the user's foot from slipping off the foot disk. The body 182 isdefined along its bottom peripheral surface by annular lip 188surrounding chamber 190 formed inside the bottom of the disk. The footdisk 180 is positioned on top of opening 42 of skateboard deck 12 andupper bearing housing 60 with the chamber 63 accommodating the upperportion of the housing. A plurality of bolts 192 pass through aplurality of holes 186 formed within the foot disk. The end of the bolts192 are screwed into the holes 152 formed within crank shaft 140. Inthis manner, when the user turns the disk pad 180 with his foot whileriding skateboard 10, the crank shaft 140 connected to the foot pad 180by means of the bolts 192 will turn in the same direction and to thesame degree.

The foot pad should ideally extend 1/16-⅛ inch above the skateboard deck12 to enable the user's foot to find the foot pad by touch withouthaving to look at the deck. This is particularly important during theexecution of a skateboard trick or aerial maneuver.

Crank shaft receptor 200 is shown in FIGS. 18-19. It comprises a roundmain body 202 and an annular skirt 204 extending laterally around theperimeter of the top of the main body. The main body features anexterior surface 206 and a flat bottom surface 208. A plurality(preferably five) of threaded bores 210 are formed in the main bodyaround its perimeter region. The annular skirt 204 has a bottom surface212 that surrounds the main body side walls 206. A plurality ofreception holes 214 are also formed in the main body 202 foralternatively receiving drive peg 158 of crank shaft 140, as describedbelow.

The truck 251 of wheel assembly 250 is shown in FIGS. 20-21. The truckprovides the necessary axle assembly for connecting the wheels 266 tothe deck 12 of the skateboard 10, and sustain the weight-bearing load ofthe user riding the skateboard.

A base plate 252 comprises a unitary construction featuring a topportion 254 having a flat top surface 255, and a lower body portion 256.End 256 a of the lower body portion of the base plate 252 is orientedtowards the center of the skateboard deck 12 when the base plate issecured to the deck, while end 256 b is oriented towards the forward(tip) end or back (tail) end of the deck, depending upon which end ofthe deck the resulting truck 251 is secured to. A partially-threadedbolt 257 called a “kingpin” extends through hole 253 in the flat, upperportion 254 of the base plate and then downwardly through, a channel(not shown) formed within end portion 256 a of the base plate.Meanwhile, a hollowed receptacle 258 called a “pivot cup” is formedwithin end portion 256 b of the base plate lower body. Finally, holes259 are formed near each of the four corners of the flat top portion 254of the base plate 252.

Hanger 260 contains a through channel (not shown) with a metal axlerunning through it extending from it on either side. Machined into theupper region 262 of the hanger is a hole 263 (not shown) for receivingthe kingpin 257. A pivot point 264 extends in an upwards and forwarddirection from the hanger 260 when, e.g., the hanger is part of a fronttruck for the skateboard.

Wheels 266 made from a durable but cushioned material that provides somemeasure of traction like polyurethane or other polymer plastic areconnected to each end of the axle of the hanger 260 to freely rotatewith respect to the axle. The hanger 260 is connected to base plate 252with pivot point 264 of the hanger extended into pivot cup 258 of thebase plate 252, and kingpin 257 of the base plate extending downwardlythrough the associated hole 263 formed with the hanger 260. A nut 268 istightened along the threaded end of kingpin 257 to secure the hanger tothe base plate. This king pin 257 enables the base plate 252 to rotateslightly with respect to hanger 260 as the user leans to one side of theskateboard in the conventional manner to steer it.

Bushings 270 and 272 represent donut-shaped polyurethane pieces that areinserted onto the kingpin 257. Upper bushing 270 is positioned along thekingpin 257 between the body end portion 256 a of the base plate 252 andhanger 260. Lower bushing 272 is positioned along the kingpin 257between the hanger and tightening nut 268. These bushing provide somemeasure of shock absorbency to the skateboard 10 to enable amore-comfortable ride for the user as he travels over bumps or hits theground following a jump or other aerial maneuver. The bushings alsocompress on one side to allow the board 12 to lean with respect to thewheels 266.

Moreover, adjusting the kingpin nut 268 to tighten or loosen thebushings 270 and 272 will adjust the turning radius and response of thetruck 251, itself. Tighter bushings will typically provide a stiffertruck with less opportunity for Wheel bite. On the other hand, looserbushings generally provide easier turning of the skateboard, but with agreater propensity for wheel bite. In this manner, the skateboard'struck 251 can be adjusted for the preference and skill level of the enduser.

A pivot bushing 274 in the form of a plastic cup-shaped piece restsinside the pivot cup 258 of the base plate 252 to support the pivotpoint 264 of the hanger 260 extending into the pivot cup. This allowsthe truck 251 to pivot smoothly. The pivot bushing 274 acts to preventfrictional contact between the hanger's pivot point 264, and the baseplate's pivot cup 258, while providing cushioning along this criticaljunction.

Suitable wheel truck assemblies for purposes of this invention may besourced from Independent Trucks distributed by www.SkateAmerica.com.Such truck assemblies normally are available within the commercialmarket with hangers defining a range of different distances between thewheels (e.g., 146, 156, or 179 mm), different wheel sizes andcompositions providing different types of rides, and bushings supplyingdifferent levels of cushioning and turning radius for the skateboard.Because of the design of the mechanical interface of the skateboard 10between the board deck 12 and the truck assemblies 151 for allowing theuser to maneuver the directions of the truck assemblies from the deck,and automatically return the truck assemblies to their standby,true-north positions, it is simple and easy for the user to customizethe trucks, wheels, bearings, and bushings from a large array ofcommercially-available products, using a conventions skateboard key.Such an approach can tailor the performance of the skateboard to thetechnical characteristics that the user depending upon his or herexperience and skill level, as well as the user's desired aestheticappearance for the skateboard.

Truck plate 240 for wheel assembly 250 is shown in FIGS. 22-23. Itcomprises a rectangular body 242 having holes 244 near its four corners.Circular ring wall 246 is integrally formed in the truck plate to extendabove the rectangular body. Ring wall 246 defines reception region 247for crank shaft receptor 200. Five holes 248 are formed within thisreception region 247 of the rectangular body 242. Studs 249 having ahead 249 a and a threaded shank 249 b are inserted through holes 244 toextend below the rectangular body.

Lower bearing housing 110 contains a roller bearing 220 and a snap ring230 that are of the same construction and design as roller bearing 116and snap ring 130 discussed above.

Wheel assembly 250 is completed by connecting truck plate 240 to baseplate 254 of truck 251 by means of the threaded studs 249. The ends ofthe studs 249 are inserted through holes 258 formed in the base plate254 so that the bottom surface 242 a of the rectangular body 242 of thetruck plate 240 abuts top surface 256 of truck 251. Nuts 270 are thenattached to the threaded regions of the shank 249 b of the studs tosecurely connect the truck plate 240 to the truck 251.

Meanwhile, crank shaft receptor 200 is inserted into the open chamber 63of lower bearing housing 110 with side wall 206 of the crank shaftreceptor abutting interior wall 124 of roller bearing 220. Peripheralskirt 204 of crank shaft receptor 200 abuts top surface 72 of the lowerbearing housing. Meanwhile the lower bearing housing 110 is insertedinto opening 98 formed in the housing 84 of the north-seeking returnmechanism 42 with exterior surface 68 of annular ring wall 66 abuttinginner wall 100 of the housing opening 98 and lugs 74 in the lowerbearing housing 110 fitting inside cars 102 within the top surface 65 ofdisk 62 of lower bearing housing 110 abuts bottom surface 82 of thehousing surrounding the opening 98 in the housing. A plurality of bolts276 pass through channels 76 formed inside lugs 74 and into threadedholes 172 formed in the housing 84. In this manner, lower bearinghousing 110 is secured to housing 84 of the north-seeking returnmechanism 42. At the same time, crank shaft receptor 200 can freely turninside the opening 98 in the housing 84.

Drive peg 160 of crank shaft 140 extends down into housing 84 and isinserted into one of the holes 214 formed in crank shaft receptor 200(see FIGS. 18-19). Bushing 162 inserted around drive peg 160 provides asecure fit of the drive peg of crank shaft 140 into the hole 214 ofcrank shaft receptor 200. In this manner, the upper bearing housing 60is coupled to the lower bearing housing 110. When the user riding theskateboard 10 turns foot disk 180 with his foot in a counter-clockwisedirection B (see FIG. 3), because the foot disk is operatively connectedto crank shaft 140 via bolts 192, which in turn is operatively connectedto crank shaft receptor 200 via drive peg 160, which in turn isoperatively connected to truck plate 240 via bolts 278, which in turn isoperatively connected to truck 151 via studs 249, the truck 151 will beturned in the same counter-clock wise direction B and to the samedegrees of rotation as the foot disk 180 was turned. In this manner, theuser can freely and confidently maneuver, e.g., the front truck 151 ofthe skateboard 10 while riding the skateboard without any need to usehis other foot to laterally push off the ground or lean his body towardsthe right side of the skateboard as is necessary to steer a conventionalskateboard with fixed wheel assemblies. Note that the rear wheelassembly 250 of skateboard 10 may comprise this same or similaruser-maneuverable assembly so that the user may independently steer thefront and rear wheel assemblies while riding the skateboard for optimalmaneuverability and control. The enhanced maneuverability and controlproduced by skateboard 10 of the present invention can be highlybeneficial to beginners learning to ride a skateboard, convenient forusers traveling recreationally along a street or park, or enabling formore advanced users who want to perform tricks.

In a preferred embodiment of the present invention, the lower bearinghousing may be integrally formed within the north-seeking returnmechanism housing 84 without a separate lower bearing housing 110, asdescribed above. As shown in FIGS. 24-25, the opening 98 of the housing400 does not feature the plurality of ears 102 shown in FIG. 8, nor thesmooth side wall 100. Likewise, the annular ring wall 66 and pluralityof lugs 74 shown in FIG. 7 are absent. Instead, side wall 402 of thenorth-seeking return mechanism housing 400 defines the cylindricalchamber 404 formed by the side wall 402, bottom ledge wall 406, andperipheral lip 408. In this manner upper roller bearing 116 is press fitinto the cylindrical chamber 65 formed inside upper bearing housing 60defined by side wall 70 and bottom ledge wall 69, and peripheral lip 71.Exterior surface 120 of roller bearing 116 abuts side wall 402 of theintegral chamber 404, while the bottom surface of roller bearing 116abuts bottom ledge wall 406. Peripheral lip 408 of the housing 400extends partially over the top of roller bearing 116 to keep it securelyin position inside chamber 404 of the housing 400. Snap ring 130 (seeFIG. 13) is then snapped into position to engage peripheral lip 408 andkeep roller bearing 116 in a fixed relationship to the housing 400. Theplurality of ball bearings 126 contained inside annular channel 124 (notshown) extend above the roller bearing inside chamber 404.

The housing 400 that integrally includes the structural features of thelower bearing housing 110 made from a non-plastic material likealuminum, steel, or stainless steel, which may be stronger than polymerplastics including polycarbonate. It preferable is made from aluminum.Also, a single housing 400 containing the lower bearing housing features110 provides greater strength than separate housing 84 and lower bearinghousing 110 described above. This enhanced strength is particularlyimportant for skateboard 10, given the significant downward forces of5,000 pounds typically applied to the truck assemblies 250 when theskateboard lands on the ground or skateboard ramp following an aerialmaneuver. This preferred design will help to prevent the truckassemblies 250 from breaking loose from the skateboard deck 12.

Moreover, a user performing aerial tricks on a skateboard that requiresturning of the trucks 251 of the wheel assemblies 250 may encounteruncertainty about which direction the wheels (particularly the frontwheels) will be pointed when the skateboard lands once again upon theground. The wheel assemblies may even turn randomly with respect to thelongitudinal axis A-A of the skateboard deck while the skateboard is inthe air during the course of the aerial trick. Indeed, a skateboardhaving two truck assemblies pointed in different directions during anaerial maneuver can provoke a nose dive by the tip or tail of theskateboard which causes an unsafe condition for the user. Therefore, theskateboard 10 of the present invention has been provided with anorth-seeking return mechanism 42 that will automatically return themaneuverable wheel assembly 250 back to its “true north” position inwhich the transverse axle 260 axis T-T is approximately perpendicular tothe longitudinal axis A-A of the skateboard deck 12 when the userremoves foot pressure from the foot disk 180 on the skateboard deck.

As shown more clearly in FIG. 26, piston shaft 300 comprising acylindrical shaft is inserted through channel 92 a and channel 92 b insquare bosses 90 on either side of open faced well 94 a. Likewise,piston shaft 302 is inserted through channel 92 c and channel 92 d insquare bosses 90 on either side of open-faced well 95. Set screws 304are inserted into a threaded region of the outside ends of the channels92 a, 92 b, 92 c, and 92 d to securely retain the piston shafts 300 and302 in place traversing the open-faced wells 94 and 95 in housing 84.

Meanwhile Scotch yoke 308 and compression springs 310 and 312 arepositioned along piston shafts 300 and 302 within the open-faced wells94 and 95. As shown more clearly in FIGS. 27.28. Scotch yoke comprises aflat main body 316 having a leading edge 318 and a trailing edge 320. Anopen window region 322 is formed within main body 316 having a forwardbearing surface 324 and a rearward bearing surface 326. Extending fromthe ends of main body 316 are wings 330 and 332 having cylindricalthrough channels 334 for accommodating piston shafts 300 and 302. Inthis manner, Scotch yoke lies on top of housing 84 and over opening 98with piston shafts 300 and 302 inserted through channels 334 of wings330 and 332, respectively, of the Scotch yoke, so that the Scotch yokemay travel in a linear direction along axis X-X, Bushings 338 areinserted inside channels 334 to reduce the friction produced by theScotch yoke 308 as it travels along the piston shafts 300 and 302. Apair of C-clips 340 are snapped into annular channel 342 formed aroundthe periphery of each end of the wing 330, 332 of the Scotch yoke toretain bushing 338 inside the channel 334 of the wing as the Scotch yokemoves along the piston shaft.

The assembled north-seeking return mechanism 42 of the present inventionis shown in its stand-by, “true north” position in FIG. 29. Drive peg160 of crank shaft 140 is inserted through window region 322 of Scotchyoke 308 and then into hole 214 of the crank shaft receptor 200. In thisposition, the transverse axle 260 of wheel truck 251 will beapproximately perpendicular to longitudinal axis A-A of skateboard deck12.

When the user's foot turns disk pad 180 in either a clockwise orcounterclockwise direction B (see FIG. 3), crank shaft 140 with itsdrive peg 160 will be rotated in the same direction B. In so doing,drive peg 160 will be pushed against forward surface 324 of window 322of Scotch yoke 308 to move the Scotch yoke along the piston shafts 300,302 along the X axis with the leading edge 318 of the Scotch yoke movingtowards the interior region of the longitudinal axis A-A of theskateboard deck (see FIG. 30). Compression springs 310, 312 will becompressed between wings 332, 334 of the Scotch yoke and square posts 88of housing 84. In this partially-turned position, drive peg 160 has beenrotated counterclockwise in the B direction and the wheels 266 of thetruck 251 have been turned to the left.

If the user continues to turn the disk pad 180 on the skateboard deck 12to the left (i.e., counterclockwise direction), then the crank shaft 140and its drive peg 160 will continue to be rotated in thecounterclockwise 13 direction as shown in FIG. 31, and Scotch yoke 308will be pushed further along the piston rods 300, 302 towards theinterior region of the axis X-X, further compressing compression springs310 and 312 between the wings 332, 334 of the Scotch yoke and squareposts 88 of housing 84. Meanwhile, the wheels of the skateboard will befurther turned to the left.

But, when the user removes foot pressure from the foot disk 180 on theskateboard deck 12, which may be done while the skateboard is in the airduring an aerial trick, the crank shaft 140 and its drive peg 160 willno longer be turned and retained in the counterclockwise position. Thisallows the stored energy in the compression springs 310, 312 to returnthe compression springs to their expanded state. The compression springswill push against the wings 330, 332 of the Scotch yoke 308 to move itback along the X-X axis towards the end region of the axis. Rearwardedge 326 of window region 322 of the Scotch yoke will be pushed againstdrive peg 160 to rotate it in a clockwise direction towards thepartially rotated position depicted in FIG. 28 to return to the standby“true north” position shown in FIG. 27. Note that the forward edge 324of window 322 of the Scotch yoke main body 318 is angled to formV-shaped legs 324 a and 324 b with “resting position” 325 provided atthe vertex point (see FIGS. 27-28). This geometry assists the return ofthe drive peg 160 to the resting position 325 which corresponds to thestandby true north position shown in FIG. 29. This will cause the wheelassembly 250 to be returned to a position with the wheels approximatelyperpendicular to the longitudinal axis A-A along the skateboard deck 12,so that the skateboard may move forward dependably as the user lands theskateboard on the ground to complete his aerial trick.

Under some circumstances, the user may wish to restrict the turningradius of the skateboard wheels. This could be convenient for beginnerskateboarders. Alternatively, it could increase the difficulty of aerialtricks during competitions for more advanced skateboarders.

Rotation limitation plate 350 (see FIG. 26) comprises an elongated,rectangular body 352 having an abutment edge 354 at its one end and ahandle 356 at its other end. This rotation limitation plate 350 isslided along channel 358 formed in housing 84. A gap G is formed betweenthe abutment edge 354 of the rotation limitation plate 350 and theleading edge 318 of Scotch yoke 308. As the user turns disk pad 180 onskateboard deck 12 to turn the wheel assembly 250 and cause the linearmovement of Scotch yoke 308 along axis X-X, as described above, theleading edge 318 of the Scotch yoke 308 will come into contact withinthe abutment edge of the stationary rotation limitation plate 350, asshown in FIG. 33. This will prevent further turning of the skateboardwheels. A smaller gap G will produce a more limited turning arc for theskateboard wheel assembly. A larger gap G will allow a larger turningarc for the wheel assembly. In this manner, the user can pre-positionthe rotation limitation plate in its inserted position along channel 358in housing 84 to adjust the degree of wheel turning arc that will bepermitted.

Note that other mechanism assemblies, including a thumb screw (notshown) that interacts through hole 360 formed in housing 84, may beutilized to make this adjustment of the rotation limitation plate alongthe channel 358 easier to accomplish.

The user-maneuverable truck assemblies and north-seeking returnmechanisms of the present invention may also be applied to otherwheel-bearing, foot-propelled roller board vehicles like non-motorizedscooters. As shown in FIGS. 35-36, such a scooter 420 comprises anelongated deck 422 made from an appropriate material such as wood,fiberglass, or plastic. The deck 422 has a top surface 424 and a bottomsurface 426. It also typically features a rounded front end 428 and arounded rear end 430 that avoids sharp edges that could collide with acurb, wall, or other impediment where a user is riding the skateboard,or injure the user during a fall or crash. The deck 422 will beapproximately 27-33 inches long. The deck 422 may optionally containalong all or a portion of its top surface 424 a panel oftraction-providing material like coated grip tape or a painted coatingcontaining abrasive particles to help to maintain the user's foot fromslipping off the board. Likewise, the top or bottom surface of the deckmay contain graphical material used to provide an appealing design tothe skateboard. The scooter 420 also has a longitudinal axis B-B runningalong its length L.

Mounted to the bottom surface 426 of scooter deck 422 are a plurality ofwheel assemblies 434, typically two in number shown as 436 and 438. Onewheel assembly 436 should be located near the front of the deck, and theother wheel assembly 438 should be located near the rear of the deck toprovide a stable ride to the user. Each wheel assembly 436, 438comprises a truck 440 having a flat planar top surface 442, and atransverse axle 444 connected to its bottom surface 446. A single ordouble wheel 446 is connected to the axle 444. The wheels are made froma suitable material like polyurethane that provides durability over timeas the skateboard is ridden by the user on abrasive surfaces likeconcrete or asphalt, while also providing some measure of cushion to theuser as the skateboard wheels travel over bumps along the riding surfacelike a street, driveway, sidewalk, trail, or ramped skateboard park. Inits standby position, the transverse axle 444 is defined by transverseaxis T-T which is approximately perpendicular to longitudinal axis B-Bof the skateboard deck 422. In this manner, the scooter 420 travels onits wheels in a forward or backwards direction substantially parallel tolongitudinal axis B-B.

The front wheel assembly 436 of scooter 420 may be pivoted by means ofhandlebar 450, so that the transverse axis T-T of the axle 444 can bemaneuvered by the user's hands to turn at an angle β with respect to thelongitudinal axis B-B of deck 422 that is greater than or less than 90°.The rear wheel assembly (not shown) may comprise a transverse axle 444that is fixed with respect to the longitudinal axis B-B as is known inthe prior art. Alternatively, this rear wheel assembly may comprise asecond pivotable wheel assembly that can be maneuvered by the user'sfoot while riding the skateboard. In the case of two such pivotablewheel assemblies, they may be maneuvered by the user's hands and footindependently with respect to each other. The pivotable wheel assemblies436, 438 may be maneuvered by the user along a full 360° arc of motion.Alternatively, the permitted arc of motion may be restricted to lessthan 360°, as described below.

Indeed, the truck for the scooter wheel assembly 434 is the same as thetruck 251 shown in FIGS. 20-21 and described above. The rear truckshould typically have a conventional hanger/axle defining a distance of,e.g., 146, 156, or 179 mm between the two wheels in order to provide sstable ride for the scooter. Meanwhile, the forward truck should havefeature a shorter hanger/axle between the two wheels in order to make iteasier for the user to turn the front wheel, while the scooter ismoving. Such a distance for this forward hanger/axle might be about ½-1inch. Alternatively, the front axle may comprise a single wheel mountedalong the axle like a roller blade wheel (see FIG. 37).

The scooter assembly 460 of the present invention havinguser-maneuverable wheel assemblies 436, 438 and a north-seeking returnmechanism 462 are shown in the exploded view of FIG. 38. In the casewhere the skateboard 10 features two user-maneuverable wheel assemblies436, 438, the deck 422 of the scooter comprises a pair of openings 464.Each opening is preferably circular in shape, although any other shapewill suffice. The openings and surrounding deck region bear the samestructural features as those shown in FIGS. 4-5 described above.

As shown more clearly in FIG. 39, handlebar 450 comprises a post 466that is vertically-oriented with respect to scooter deck 422. Handle 468connect transversely to the top of the post 466 provides means for theuser's hands to maneuver the handlebar 450 to steer the scooter. At thebottom of post 466 mounting base 470 having a plurality of holes 472(preferably five) formed there through. A decorative bell-shaped cowling474 having a hole in it slides along post 466 to cover the mountingassembly of the handlebar to the scooter deck, as described below. Aplurality of holes 476 are formed around the periphery of cowling 474for screws 478. Moreover, this bell-shaped cowling provides stability tothe vertically-mounted post 466 so that the user does not accidentlypull it towards the deck of the scooter during a maneuver.

For purposes of the scooter 420, the upper bearing housing 60, upperbearing 116, crank shaft 140, housing 84 for the north-seeking returnmechanism, crank shaft receptor 200, lower bearing 116, and lowerbearing housing 110 are the same in terms of structure and function asthe corresponding parts described above for skateboard 10. Instead offoot pad 180 being connected to crank shaft 140 by means of bolts 192,mounting base 470 on handle bar post 466 is connected to crank shaft bymeans of bolts 480. Thus, when the user turns handlebar 450 with respectto longitudinal axis B-B of the deck 422, crank shaft 140, which isoperatively connected to crank shaft receptor 200, which is operativelyconnected to the truck for wheel assembly 466 will likewise be turned inthe same direction to the same degree. Similarly, when the user releasesforce from the handlebar, the north-seeking return mechanism 82 willoperate as described above to automatically turn the axle of wheelassembly 466 hack to its standby position which is parallel to thelongitudinal axis B-B. If the rear wheel assembly 468 is operativelyconnected to a foot disk 180 mounted into the scooter deck 422, asdescribed above, the user can use his rear foot to steer the rear wheelassembly by means of the foot disk independently of the front wheelassembly 466 which is turned by means of handlebar 450.

While the integrated housing 400 that incorporates the lower bearinghousing 110 may provide greater strength than the separate north-seekingreturn mechanism housing 84 and lower bearing housing 110, describedabove and shown in FIGS. 3 and 25, it has been discovered that undersome circumstances this structure may be insufficient to withstandaggressive tricks performed on the skateboard. More specifically, duringaerial maneuvers, the wheel assemblies 250 of the skateboard can land onthe ground with 5,000 pounds of downwards force. Such significant threesapplied to those wheel assemblies can cause the snap ring 230 to becomedisengaged from the housing 400 (or the lower bearing housing 110 ifsuch a separate bearing housing is used. But, the snap ring is employedto secure the lower bearing 220 in position inside the bearing housingor its equivalent structure inside north-seeking return mechanismhousing 400. If the bearing 220 becomes detached from the bearinghousing, then the wheel assembly 250 will not be turned properly bymeans of the rotated foot pad 180.

In response, a retention plate 502 is substituted for the lower snapring 230, as shown more clearly in the exploded FIG. 40A view of thismodified embodiment of the skateboard assembly 500, As shown in FIGS.41-42, this retention plate 502 comprises a flat, round plate 504defined by an annular region 506 with a plurality of holes 508. Roundopening 510 is defined by the annular region of the plate.

The retention plate 502 is attached to the bottom surface of lowerbearing housing 110 or integrated north-seeking return mechanism housingby means of a plurality of bolts 512. In this manner, the retentionplate 502 securely maintains lower bearing 220 inside the internalchamber of the lower housing 110 or integrated north-seeking mechanismhousing 400 so that truck plate 240 rotates smoothly with respect to thehousing attached to the bottom of the skateboard deck 12. This, in turn,enables the wheel assembly 250 to be smoothly rotated by means of footpad 180 when the user's foot turns the foot pad, and the north-seekingreturn mechanism 84 to counter-rotate the foot pad and associated wheelassembly 250 back to its true-north position when the user's foot nolonger applies rotational force upon the foot pad.

The north-seeking return mechanism 84 of the present invention iscrucial for counter-rotating the foot pad 180 and the associated wheelassembly to their true-north position. This feature ensures that theaxles of the front and rear Wheel assemblies will be approximatelytransverse to the longitudinal axis A-A of the skateboard deck 12 whenan aerial maneuver is completed. Otherwise, if the front and rear wheelassemblies land upon the ground out of transverse alignment, the nose ortail of the skateboard can dip towards the ground in an unpredictablemanner to ruin the aerial maneuver or threaten the safety of theskateboard rider.

However, the operation of this north-seeking return mechanism isdependent upon the compression springs 310, 312 contained inside thehousing 84 (see FIGS. 29-31). The foot pad 180 and wheel assembly 250are counter-rotated to their true-north position as the energy stored inthe compression springs expands the compression springs to theiroriginal, non-compressed length to push the Scotch yoke back along thepiston rods 300, 302 to its standby position. But, thecounter-rotational response of the north-seeking, return mechanism 42may be modified by adjusting the preload of the compression springs 310,312.

As shown in FIG. 43, a spacer 520 may be inserted inside the housing 84of the north-seeking return mechanism 42. This spacer comprises acylindrical body 522 formed from a suitable material like plastic ormetal with a through bore 524. The spacer 520 is inserted around pistonrod 300, 302 between one end of compression spring 310, 312 and theinterior wall of the square shaped boss 88 of the housing. The spacer520 has a length L.

The spacer 520 acts to take up space along piston rod 300, 302 insideopen-faced well 94, 95, and apply a preload upon compression spring 310,312 inside the open-faced well in order to increase the compression loadupon the spring when the return mechanism 42 is in its true-northposition (FIG. 43). As the compression spring 310, 312 is furthercompressed inside the open-faced well of housing 84 as the foot pad 180is rotated by the user's foot to move the Scotch yoke 308 linearly alongpiston rods 300, 302 (See FIGS. 30-31), the compression load will befurther increased upon the compression spring. But when the userreleases the rotational foot force upon the foot pad 180, thecompression spring 310, 312 will expand to its original length with evengreater force than if the spacer 520 were not present in the housing 84.This increased compression load will cause the enhanced force to beapplied against the Scotch yoke to move it more quickly along the pistonrods 300, 302, counter-rotating the crank shaft receptor 200, crankshaft 140, and foot pad 180 in the process.

A variety of spacers 520 of different lengths L may be selecteddepending on the preload force that the user wants to apply to thecompression spring 310, 312 in its standby state. The lengths L of thespacer should be ⅛-¼ inch, preferably an ⅛ inch.

In an alternative embodiment 530 depicted in FIG. 44, an adjustable nut532 may be used in lieu of spacer 520. This threaded nut 532 bearshelical threads 534 along its inner surface. These threads cooperatewith helical threads 536 formed along the exterior surface of piston rod300, 302. The bearing face 538 of nut 532 will act to apply a preloadupon compression spring 310, 312 in a similar manner to the spacer 520embodiment of FIG. 43. However, the position of the nut 532 isadjustable along piston rod 300, 302 to allow the user to increase ordecrease the preload force applied upon the compression spring 310, 312in its standby condition. This adjustable nut 532 eliminates the needfor a number of spacers 520 of different lengths L. It also eliminatesthe need for the user to disassemble north-seeking return mechanism 42to insert spacer 520, or swap out a spacer of a different length L toadjust the preload three applied to the compression spring 310, 312.

Depending upon the size of the user's foot, the shoe may extend beyondthe perimeter of foot pad 180 to accidentally engage deck 12. Draggingthe foot across deck 12 can impede the foot's rotation of foot pad 180and its associated wheel assembly 250. Therefore, in another embodimentof the present invention, an enlarged foot pad 530 can be used, as shownin FIGS. 40A and 40B. Such an enlarged foot pad 530 has a largerdiameter than foot pad 180 shown in FIG. 3. This enlarged foot pad 530should have a diameter range covering the full range of adult andchildren's shoe or foot lengths.

However, as the diameter of the foot pad 530 is increased, it willbecome much larger than the diameter of the upper bearing housing 60 andconsequently opening 44 in the skateboard deck 12. Thus, instead ofhousing the foot pad fit inside the deck opening so that its top surfaceis substantially co-planar with the top deck surface, as described aboveand shown in FIG. 1, enlarged foot pad 530 is positioned on top of deck12, as shown in FIG. 40B. At the same time, a plurality of low-frictionpads 532 are secured to the bottom surface of foot pad 530 around itscircumference, as shown in FIG. 45. Such low-friction pads 532 are flatwith holes 534 for accommodating bolts 536 that secure the pads toopenings (not shown) formed within the bottom surface of the foot pad.

The foot pads 532 should be made from a suitable plastic polymermaterial that has a low coefficient of friction. Such a materialincludes Delrin® (acetyl homopolymer) made by DuPont. A complete ring ofthe low-friction material may cover the circumference of the foot pad530. But, a plurality of discrete portions of the spacer material, suchas four pieces 532, is preferred. The spacers act to reduce frictionaldrag as the user's foot rotates the loot pad 530 along the top surfaceof the skateboard deck 12. Moreover, the pads 532 act to provide lateralstability to the foot pad so that it does not wobble during operationwith respect to the top surface of the deck.

As shown in FIG. 21, truck 251 employs upper bushing 270 and lowerbushing 272 spaced along king pin 257 between base plate body 256 andhanger 260. These bushings typically formed from a resilient polymermaterial like polyurethane provide some measure of shock absorbency tothe skateboard as the user travels over humps or hits the groundfollowing a jump or aerial maneuver.

But the bushings 270, 272 also compress on one side of the truck 251 toallow the board 12 to lean with respect to the wheels 266. This allows auser to turn the board direction above and beyond the action of themaneuverable foot pads used to turn the wheel assemblies. King pin nut268 may be tightened or loosened to increase or decrease the degree ofbushing compression to adjust the turning radius and response of thetruck. Less compressed bushings produce easier turning of theskateboard, which can be helpful for novice riders.

However, a novice or inexperienced rider can be further assisted byreplacing the polyurethane or rubber bushings 270, 272 with bushingsmade from a hard material like nylon, polyesterimide (“PEI”) plasticslike ULTEM® plastic sold by Plastics international of Eden Prairie,Minn., or polyaryletherketone plastics like polyether-ether-ketone(“PEEK”) plastics. These are materials exhibiting a high durometervalue. This hardened material for the bushings will facilitate turningthe board direction via the user leaning his body with respect to theboard. This reduces the need to turn the wheel assemblies 250 via thefoot pad 180, 530.

One of the effects produced by the user-maneuverable wheel assemblies ofthe present invention is that the skateboard user, especially skilledriders, turn out to ride the foot pads 180 with their feet rather thanthe deck 12 of the skateboard, itself. This result reduces the need fora continuous solid deck 12 that is conventional for skateboards.

An alternative embodiment 540 of the “deck” is shown in FIG. 46comprising a tubular structure. A small front deck 542 and rear deck 544are connected to each other by means of longitudinal tubes 546 and 548.The front deck 542 and rear deck 544 each comprise an opening 550 and552, respectively that is similar to openings 44 formed in deck 12 (seeFIG. 3), and accommodate the upper bearing housing 60 and crank shaft140 described above for the rotatable foot pad 180. The front deck 542and rear deck 544 also comprise the plurality of threaded holes 554around the perimeter of openings 550 and 552 for receiving the boltsused to attach the housing 84 for the north-seeking, return mechanism42, as described above. Such a tubular structure for the skateboard“deck” 540 made from steel or other metal can be cheaper to manufacturethan conventional decks 12 made from fiberglass or other compositeplastic materials. At the same time, a metal structure exhibits thenecessary strength to resist the forces applied upon the deck and wheelassemblies during aerial tricks and maneuvers. Meanwhile, the user caneasily stand with his feet upon the two foot pads 180, 530.

A simpler north-seeking return mechanism 560 is depicted in FIG. 47. Thefoot pad 562 is operatively attached to deck 12 using the upper bearinghousing 60. It turns the wheel assembly 250 by means of the rotarycrankshaft 140 and crankshaft receptor 200 also described above.However, instead of the relatively complicated north-seeking returnmechanism 42 containing the Scotch yoke 308, piston rods 300, 302, andcompression springs 310, 312 described above, the mechanism 560 includesa housing 568 attached to the bottom of the deck into which the crankshaft attached to the foot pad 562 depends. Two coil springs 564 and 566are also contained inside the housing 568. One end of each of thesprings 564, 566 is attached to the 9:00 (left) and 3:00 (right) sidepositions, respectively, of the crank shaft 140. The other ends of thecompression springs are attached to the forward interior wall 570 of thehousing 568.

In FIG. 47, the wheel assembly is in the true-north position. When theuser's foot turns the foot pad 562, e.g., in a clockwise direction, thewheel assembly will be turned in a rightward direction via theinterlocking crank shaft 140, crank shaft receptor 200, truck plate 240,and wheel assembly 250 that are operatively connected to the rotatedfoot pad 562. Bearings contained inside the upper and lower bearinghousings ensure smooth turning operation. At the same time, theclockwise turning of the foot pad will compress coil spring 564 andstretch coil spring 566. When the user removes the rotational forceapplied by his foot to foot pad 562, the energy stored in the springswill cause compression spring 566 to push the crank shaft in acounterclockwise direction, while compression spring 564 pulls the crankshaft also in the counterclockwise direction, thereby resulting in thefoot pad and wheel assembly being counter-rotated toward the true-northposition. If compression springs 564 and 566 are properly balanced interms of their length and resistance, this mechanism 560 will result inthe wheel assembly recovering its true-north position. Meanwhile, thismechanism has fewer parts than the true-north recovery mechanism 42described above, for the two coil springs perform the recovery functionwithout having to convert the rotational movement applied to the footpad into linear movement of a Scotch yoke contained inside the housing.This alternative north-seeking return mechanism 560 should accommodateapproximately a 90 degree range of rotation for the wheel assembly,instead of the 360 degree range of rotation permitted by the Scot yokeof the true-north return mechanism 42.

Yet another embodiment of a north-seeking return mechanism 580 incombination with a tubular “deck” 582 for a skateboard is shown in FIGS.48-50. As shown in FIGS. 48A and 48B, a front foot pad 584 is connectedto the top end 586 of a crankshaft 588. The lower end 590 of thecrankshaft 588 is connected to the truck of a wheel assembly 592.Similarly, a rear foot pad 594 is connected to the top end 594 of asecond crankshaft 596. The lower end 598 of the crankshaft is connectedto the truck of a second wheel assembly 600. The crankshafts arecontained in a forward housing 602 and a rear housing 604. Tubularsupport 606 connects the forward housing 602 and rear housing 604, anddefines a longitudinal axis C-C for the north-seeking return mechanism580.

As shown more clearly in FIGS. 49A and 49B, the crankshaft 588 and 596comprise flat-plane crankshafts. Each one is vertically mounted in itsrespective housing along a vertical axis D-D. An inlet crank portion 610and outlet crank portion 612 are connected to each other by means of aneccentrically oriented wing 614 comprising an upper horizontal leg 616,vertical intermediate leg 618, and lower horizontal leg 620. The upperand lower horizontal legs 616 and 620 are co-planar. The crankshafts arepreferably cast from a continuous piece of metal for strength andseamless motion as the crankshaft rotates about its vertical axis D-D.

Connecting rod 622 comprises a piston 624 with a circular linkage 626 atits one end. The circular linkage 626 surrounds vertical intermediateleg 618 of the eccentrically mounted wing 614 of the crankshaft. Thepiston portion 624 of the connecting rod 622 extends inside tubularsupport 606. A shoulder 628 is formed along the connecting rod 622between the circular linkage 626 portion and piston portion 624.

A foot pad 630 is attached to the inlet crank portion 610 of thecrankshaft. A bearing 632 (not shown) facilitates the rotated movementof the foot pad. The outlet crank portion 612 is attached to the truckplate 634 of the wheel assembly 592, 600. A hearing 636 (not shown)facilitates the rotated movement of the truck plate and wheel assembly592, 600. In this manner, when the user's foot rotates the foot pad inthe clockwise or counterclockwise direction, the crankshaft will berotated inside the housing in the same direction and to the same degreeas the rotated foot pad, as will the wheel assembly that is connected tothe outlet crank portion 612 of the crankshaft. Meanwhile, a compressionspring 638 surrounds the piston portion of the connecting rod. Its oneend touches shoulder 628 of the connecting rod, while its other endtouches pivot block 640 that slidably engages the distal end 642 of theconnecting rod. The pivot block 640 is located further inside thetubular support 606.

As shown in FIGS. 48A, 49A, and 50A, the true-north position for thewheel assembly where its axle is traverse to axis C-C of the tubularsupport exists when the upper and lower horizontal legs 616 and 620 ofthe eccentrically-oriented wing 614 are co-planar with longitudinal axisC-C, and the vertical intermediate leg 618 is the furthest distance fromthe tubular support. In this position, the connecting rod 622 iswithdrawn as fully as possible forward or rearward from the support tube606. The compression spring 638 resides in its low-energy state.

But, when the crankshaft 588, 596 is rotated in a clockwise orcounterclockwise direction by means of the foot pad 630, theeccentrically-oriented wing 614 and its vertical intermediate leg 618will be rotated in an arc towards the support tube. This will cause theconnecting rod 622 that is rotatably connected to the crankshaft'svertically intermediate leg 618 by means of circular linkage end 626 toextend into the hollow tubular support 606, contracting compressionspring 638 in the process.

FIG. 50A depicts the mechanism from overhead. It shows connecting rod622 pivotable connected to vertical intermediate leg 618 of thecrankshaft 588, 596 which is turned about its vertical axis of rotation646 defined by the inlet crank portion 610 and outlet crank portion 612of the crankshaft. Pivot block 640 supports the distal end of theconnecting rod 622. Compression spring 638 is supported by theconnecting rod 622 between its shoulder 628 and pivot block 640. This isthe true-north position for the associated wheel assembly of theskateboard.

When the foot pad 584, 594 is rotated 45 degrees in a clockwisedirection, as shown in FIG. 50B, the crankshaft's vertical intermediateleg 618 is rotated 45 degrees along arc D-D. This will cause theconnecting rod 622 to pivot with respect to pivot block 640 with thedistal end of the connecting rod sliding further through the pivot blockto shorten the distance E-E between the connecting rod's shoulder 628and the pivot block 640. This contracts compression spring 638 to inducea higher energy state.

If the user continues to turn foot pad 584, 594 to the 90 degreeclockwise position shown in FIG. 50C, the crankshaft's verticalintermediate leg 618 will likewise be rotated along arc D-D to the 90degree position. This will cause connecting rod 622 to further slideinwardly through pivot block 640 to further shorten compression spring638.

If the user continues to turn foot pad 584, 594 to the 180 degreeclockwise position shown in FIG. 50D, distance E-E along the connectingrod 622 is shortened still more to further contract compression spring638. This is the maximum contraction, highest energy state for thecompression spring 638 shown in FIG. 49B.

The foot pad 584, 594 can continue to be turned by the user to the 270degree position shown in FIG. 50E and the 315 degree position shown inFIG. 50F, for this north-seeking recovery mechanism allows the foot padand the wheel assembly to be turned throughout a 360 degree arc. Thefoot pad and wheel assembly can also be turned by the user in acounterclockwise direction with the same effect.

When the user's foot releases the rotational force from the foot pad584, 594, the stored energy in the retracted compression spring 638 willcause the spring to expand to its original length to push against theshoulder 628 of connecting rod 622 to extend the connecting rodoutwardly from pivot block 640 and out of the tubular support,counter-rotating the crankshaft in the process to return it to itstrue-north position. Thus, this north-seeking return mechanism 580converts the rotational movement of the crankshaft 588, 596 into linearmovement of the connecting rod 622 similarly to the north-seeking returnmechanism 42 translating the rotational movement of crankshaft 140 intolinear movement of Scotch yoke 308. Moreover, mechanism 580 enables 360degree rotation and counter rotation of the wheel assembly just likemechanism 42 achieves. But mechanism 580 uses fewer parts than mechanism42 does.

Finally, the scooter embodiment of the present invention shown in FIGS.38-39 has a handle bar post 466 that is mounted to the user-maneuverabletruck mechanism along a vertical axis. But, it may be more ergonomic forthe user to have the handle bar post raked towards the user so that hedoes not need to lean or reach as far forward to grasp the handle bar468. Moreover, a raked post will enable the front wheel assembly of thescooter to be mounted further forward along the scooter deck which canimprove the stability of the scooter as its front and rear wheelassemblies ride along the ground surface.

FIGS. 51-52 show an alternative embodiment 650. The same upper bearinghousing 60, bearing 116, crankshaft 140, crankshaft receptor 200,bearing 116, and lower bearing housing as shown in FIG. 39 are used tooperably connect the handle bar post 466 to the front wheel assembly652. But, an adaptor plate 654 is bolted onto deck 12. Universal joint656 has an upper post 658 and a lower post 660 pivoting with respect toeach other within a vertical plane by means of linkage pin 662. Thelower post of the universal joint 656 is attached to the crankshaft 140.Meanwhile, upper post 658 of the universal joint 656 is inserted intothe hollow bottom of handle bar post 466. Housing 666 has body portion668 attached to flange portion 670. The flange portion 670 is bolted todeck 12. Body portion 668 surrounds handle bar post 466 to providestructural support to the post. Handle bar post 466 is raked towards therear end of the scooter deck 12 by means of the universal joint 658 andhousing body 666. Angle γ defined between vertical axis F-F and rakedaxis G-G is about 15-25 degrees, preferably about 20 degrees.

The above specification and associated drawings provide a completedescription of the structure and operation of the skateboard havinguser-maneuverable trucks and a north-seeking return mechanism of thepresent invention. Many alternative embodiments of the invention can bemade without departing from the spirit and scope of the invention.Therefore, the invention resides in the claims herein appended.

What is claimed is:
 1. A roller board device operated by a user with oneor more user-maneuverable wheel assemblies that are automaticallyreturned to their “true north” position, comprising: (a) an elongateddeck having a longitudinal axis and one or more openings extendingthrough the deck, the deck having a top surface and a bottom surface;(b) at least one wheel assembly comprising a truck and axle with atleast one wheel rotatably mounted to the axle; (c) a rotation assemblyoperatively engaging and extending through the opening in the deck, oneend of the rotation assembly being connected to the wheel assemblypositioned below the deck, the other end of the rotation assembly beingconnected to a user interface member extending upward beyond the topsurface of the deck; (d) a north-seeking return mechanism secured to thedeck, the north-seeking return mechanism having a housing containing atleast one piston rod along which a Scotch yoke is moved along a linearaxis between a standby position and a retracted position within thehousing and engaging a spring disposed between the Scotch yoke and aninterior wall of the housing, the rotation assembly operativelyconnected to the Scotch yoke to convert rotational movement of the userinterface member into linear movement of the Scotch yoke; (e) a pre-loadenhancer positioned inside the housing along the piston rod forshortening the length of the spring when it is in a standby state; (f)wherein in its true north position, the axle of the wheel assembly issubstantially transverse to the longitudinal axis of the deck with theScotch yoke in its standby position along the linear axis inside thenorth-seeking return mechanism housing; (g) wherein when the userapplies rotational force to the user interface member to turn it to theleft or right, the rotation assembly and wheel assembly are rotated inthe same direction and degree to allow the roller board device to beturned, the rotated rotation assembly interacting with the Scotch yokeof the north-seeking return mechanism to move the Scotch yoke along itslinear axis to a retracted position to compress the spring; and (h)wherein when the user releases the rotational force upon the userinterface member, the spring extends from its compressed state to itselongated state to move the Scotch yoke of the north-seeking returnmechanism more forcefully back along the linear axis from its retractedposition to its standby position due to the preload applied to thespring by the pre-load enhancer, counter interacting with the rotationassembly to return the wheel assembly of the roller board device to itstrue north position.
 2. The roller board device of claim 1, wherein thepreload enhancer comprises a spacer.
 3. The roller board device of claim1, wherein the preload enhancer comprises an adjustable nut.
 4. Theroller board device of claim 1, wherein the spring comprises acompression spring.
 5. The roller board device of claim 1, wherein theuser interface member comprises a disk-shaped foot pad for engagement bya foot of the user.
 6. The roller board device of claim 4 furthercomprising at least one low-friction pad attached to the bottom surfaceof the foot pad to reduce friction and enhance lateral stability as thefoot pad is turned with respect to the deck of the roller board.
 7. Aroller board device operated by a user with one or moreuser-maneuverable wheel assemblies that are automatically returned totheir “true north” position, comprising: (a) an elongated deck having alongitudinal axis and one or more openings extending through the deck,the deck having a top surface and a bottom surface; (b) at least onewheel assembly comprising a truck and axle with at least one wheelrotatably mounted to the axle; (c) a rotation assembly operativelyengaging and extending through the opening in the deck, one end of therotation assembly being connected to the wheel assembly positioned belowthe deck, the other end of the rotation assembly being connected to auser interface member extending upward beyond the top surface of thedeck; (d) a north-seeking return mechanism secured to the deck, thenorth-seeking return mechanism having a planar crank shaft and aconnecting rod movable along a linear axis with respect to a pivotblock, and engaging a spring disposed between the connecting rod and thepivot block, the rotation assembly operatively connected to theconnecting rod via the planar crank shaft to convert rotational movementof the user interface member into linear movement of the connecting rodwith respect to the pivot block; (e) wherein in its true north position,the axle of the wheel assembly is substantially transverse to thelongitudinal axis of the deck with the connecting rod in a standbyposition along the linear axis inside the north-seeking returnmechanism; (f) wherein when the user applies rotational force to theuser interface member to turn it to the left or right, the rotationassembly and wheel assembly are rotated in the same direction and degreeto allow the roller board device to be turned, the rotated rotationassembly interacting with the connecting rod of the north-seeking returnmechanism to move the connecting rod along its linear axis to aretracted position to compress the spring; and (g) wherein when the userreleases the rotational force upon the user interface member, the springextends from its compressed state to its elongated state to move theconnecting rod of the north-seeking return mechanism back along thelinear axis from its retracted position to its standby position, counterinteracting with the rotation assembly to return the wheel assembly ofthe roller board device to its true north position.
 8. The roller boarddevice of claim 7 further comprising a shoulder on the connecting rodfor providing a bearing surface for interacting with the spring.
 9. Theroller board device of claim 7, wherein the spring comprises acompression spring.
 10. The roller board device of claim 7, wherein therotation assembly comprises: (a) a rotary crank shaft; (b) a rotarycrank shaft receptor; (c) the planar crank shaft connected at its firstend to the rotary crank shaft, and at its second end to the rotary crankshaft receptor; (d) wherein when the rotation assembly is turned by theuser force applied to the user interface member, the crank shaft andcrank shaft assembly are rotated in the same direction and degree as theuser interface member to turn the wheel assembly of the roller boarddevice, and the planar crank shaft bears against the pivotably connectedend of the connecting rod of the north-seeking return mechanism to moveit along the linear axis to its retracted position; and (e) wherein whenthe user ceases to apply rotational force to the user interface memberand the spring in the north-seeking return mechanism housing expandsfrom its compressed state to its elongated state, the leading edge ofthe connecting rod bears against the pivotably connected planar crankshaft to counter-rotate the rotary crank shaft and rotary crank shaftreceptor to their standby positions, thereby returning the wheelassembly to its true-north position.
 11. The roller board device ofclaim 7, wherein the rotation assembly further comprises at least oneroller bearing.
 12. The roller board device of claim 7, wherein theroller board device comprises a skateboard.
 13. The roller board devicefor claim 7, wherein the roller board device comprises a scooter. 14.The roller board device of claim 7, comprising a first user-maneuverablewheel assembly operatively mounted to a forward position along the deck,and a second user-maneuverable wheel assembly operatively mounted to arearward position along the deck.
 15. The roller board device of claim7, wherein the user interface member comprises a disk-shaped foot padfor engagement by a foot of the user.
 16. The roller board device ofclaim 13, wherein the user interface member comprises a handle barconnected to a vertical shaft extending above the deck.
 17. The rollerboard device of claim 16, where the vertical shaft is raked to extend atan angle above the deck from the front end of the deck towards a userriding the scooter.
 18. The roller board device of claim 14, wherein thetwo user-maneuverable wheel assemblies may be turned by the userindependently of each other.
 19. The roller board device of claim 7,wherein the elongated deck comprises a small front deck and a small reardeck connected to each other by means of a tubular structure, a firstwheel assembly being rotatably connected to front deck, and a secondwheel assembly being rotatably connected to the rear deck.